The present invention relates to an electrically driven wheel chair comprising a vertically adjustable seat support and calf supports with a footrest member, and an extra pair of wheels, said members being connected with said vertically adjustable seat support so as to be actuated and adjusted to a desired position when the seat support is vertically adjusted.
Commonly used wheel chairs, whether electrically driven or not, are not provided with a vertically adjustable seat. But many of them are collapsible, and in this connection reference is made, inter alia, to British Patent Application No. 2,090,564 which relates to a wheel chair the seat frame of which is of a scissors linkage type having two possible positions, i.e. a completely folded, and a completely extended position. Wheel chairs of said kind create a number of problems to the user of the wheel chair. The seat portion of the wheel chair has a vertical position which may possibly be said to form a compromise of various considerations, but which will very often prove to be either too low or too high.
A wheel chair user's activities, e.g. at home, are thus at present limited by the vertical position of the wheel chair. The disabled user will commonly not be able to reach down or close enough to the floor to pick up, e.g. objects which the disabled person has dropped. On the other hand, the wheel chair user will not be at a proper level to carry out tasks, e.g. on a kitchen cabinet, or to reach far enough up into a kitchen wall cupboard. In the bathroom the disabled person in a wheel chair will either sit too low or too high, dependent on the tasks to be carried out. It is often a problem to lie down on a bed because of the difference in level between the wheel chair seat and the bed. For wheel chair users to function in the best possible manner at home, so that they may also be self-reliant to a greater extent, quite extensive changes of various installations in the home are often required. This is especially the case with existing houses or appartments.
For a disabled person's wheelchair, especially an electrically driven wheel chair, to be used for a driver's seat in a larger vehicle, like a delivery van, etc., the vertical position of the wheel chair seat portion at present requires the vehicle floor to be converted, so that the user will be at a correct level relative to various control means of the vehicle. It is desirable to lower the front portion of the vehicle floor to a suitable level, but this is only possible with one or two car makes. Commonly, the supporting structures of a vehicle will prevent conversion which involves lowering of the floor. If it is possible to convert the car in this manner, this will, however, be very expensive, as mentioned above.
In most car makes where it is impossible to lower the total floor area of the front portion of the vehicle, a limited portion of the floor must be lowered, resulting in a well-like cavity in the existing floor. With all the car makes of interest, however, a problem resides in the fact that the chassis of the vehicle with supporting structures does not permit said cavity to be placed at the required short distance to permit the wheel chair user to reach various operating means, like steering wheel, etc. Reconstruction of various operating means will be required to place them closer to the driver. Obviously, the mentioned changes which have to be made on conventional vehicles are very expensive.
Furthermore, from German Patent DE-OS No. 25 17 418 a wheel chair is known the seat portion of which is vertically adjustable at the same time as the angle of inclination of the seat level proper is adjustable. Said adjustment is carried out by the aid of two vertical piston rods which are provided at a mutual distance, and which are at their lower ends mounted on the chair support and at their opposite ends are in contact with the seat portion proper. The wheel chair according to the last mentioned patent publication, obviously, represents a considerable improvement relative to wheel chairs which are not vertically adjustable, and to some extent it partly eliminates some of the disadvantages of wheel chairs that are not vertically adjustable. A considerable disadvantage of the wheel chair according to said patent publication, however, is that the maximum lowering capacity of the seat portion will be limited by the length of the piston rod, which in turn also will determine the distance between the lowermost and the highest position of the seat portion. The greatest disadvantage, however, is the fact that the piston rod prevents extensive lowering of the seat portion. Another considerable disadvantage of the disclosed wheel chair is that two piston rods are required to provide reasonably acceptable stability of the seat portion. This is both bulky and expensive.
Another common aspect of existing wheel chairs is that the user will often find himself in a much lower position than, e.g. a person standing up, in a conversation. This is very unfortunate and may have a restraining effect on communication with other people.
Other disadvantages which may not be directly connected with the vertical position of the wheel chair user in case of conventional, and preferably electrically operated wheel chairs is that they tend to instability when driven on rough ground. Special problems also arise in connection with high kerbstones which the user of a wheel chair meet when driving onto a pavement.